Alloy



Patented May 29,- 1928.

UNITED s'rras 1,671,408 PATET OFFICE.

MICHAEL G. CORSON, F JACKSON HEIGHTS, NEW YORK, ASSIGNOR- TO ELECTBOMETALLURGICAL COMPANY, A CORPORATION OF WEST VIRGINIA.

ALLOY.

No Drawing.

The invention is an alloy useful fora variety of purposes andparticularly for diecasting.

The properties which are of most importance in metals for die-castingare, ability to give a casting having good mechanical properties, suchas strength, hardness and homogeneity; low shrinkage duringsolidification and cooling; and absence of destructive action on themolds or dies in which the cast is made.

The deterioration which dies for die-casting undergo during use is dueto an attack which is in part physical and in part chemi- 1 cal. Boththese actions, and particularly the physical one, are reduced inintensity by lowering the temperature at which casting is carried out. 1

A survey of the field indicates the desirability of copper alloys betteradapted for die-casting than those now available. The alloys of copperwith aluminum, zinc and tin respectively, have some desirable propertiesbut each is deficient in some important *espect. The aluminum bronzesrequire high casting temperatures and suffer too much shrinkage. Thezincalloys, such as Muntz metal and its known modifications, have desirablylow melting points but because of 3 their zinc content they stronglyattack all iron alloys suitable for making the molds or dies. Thecopper-tin alloys, such as admiralty metal, sufler relatively littleshrink age but do not crystallize uniformly during solidification.

The only other binary alloys of copper in which the melting point isprogressively lowered with increasing content of the metal alloyed withthe copper are the copper-mam 40 ganese alloys. These alloys exhibitanother highly desirable property for the use under discussion, viz, asthe manganese content increases and the meltin point' is depressed, thetemperature drop etween the beginning and the end of freezing becomesless, until at 34% manganese the melting point is only 875 C. and themolten alloy solidifies at practically constant temperature.

Unfortunately copper-manganese containing about 34% manganese is notsufliciently fluid when molten to produce good castings, especially ifthe mold is at all intricate, and furthermore the solid metal has poor.mechanical properties. By diminishing the manganese content to about 15%to 25%,

Application filed April 18,

of admiralty metal (88% copper, 12% tin,

1926. Serial No. 101,811.

the melting point is somewhat raised but the metal is improved in allother respects. An addition of phosphorus or silicon brings about anadditional improvement which consists mainly in further increasing thefluidity of the molten alloy. The phosphorus and silicon also have thedesirable effect of giving the alloy greater strength when it is heatedto temperatures approaching its melting point. A content of about 0.1%to 3% of either element may be used. An alloy containin about 20% ofmanganese and about 1% o phosphorus or silicon is preferred. Elementsother than copper, manganese, phosphorus and silicon may of course beincorporated for special purposes. For example, nickel and tin may thusbe added.

The preferred alloy referred to above begins to melt at 890 C. and iscompletely molten at 905 C. When molten it is sufiiciently fluid for themaking of intricate castings. It has very little effect on iron molds,chemical action being practically prevented by the film of oxide whichforms about the stream of molten alloy as it enters the mold 80 and bothchemical and physical attack are diminished by the relatively lowpouring temperature. The preferred alloy has an impact resistance onlyslightly lower than that 2% zinc) while it registers 136 Brinnellhardness and 22 scleroscope and is therefore considerably harder thaneither admiralty metal orphosphor-bronze (89.5% copper, 10% tin, 0.5%phosphorus). It also shrinks less than admiralty metal orphosphorbronze, and these in turn shrink the least of the copper alloysheretofore available. At high temperatures it great- 1y excels them instrength. It is possible to cast blanks from the phosphorusorsilicon-containing copper-manganese alloys of approximately the size andshape desired in the finished article and then to finish them by lightdrop-forging, such a procedure being quite impossible with any of thecopper-tin bronzes now used for diecasting.

In making the alloys of the invention the phosphorus or silicon ispreferably added to the melt before the manganese in order that themetal may be thoroughly deoxidized and oxidation of the manganeseprevented.

I claim: v

1. A non-ferrous alloy containing about 15% to 25% of manganese and 0.1%to 3% of an element havlng the properties of phosphorus and silicon,with the balance 5 principally copper.

non-ferrous alloy containing about 20% manganese and about 1% of anelement having the properties of phosphorous and silicon with thebalance principally copper. 3. A non-ferrous die-cast article composed10 of an alloy containing 15% to 25% of manganese and 0.1% to 3% of anelement having the properties of phosphorus and silicon, with thebalance principally copper.

4. A non-ferrous die-cast article composed of an alloy containing about20% manganese 15 and about 1% of an element having the properties ofphosphorus and silicon, with the balance principally copper.

In testimony whereof, I aflix m signature.

MICHAEL G. ORSON.

